Presses



Sheet b A a 9 7 A 5 h 3 fin. G n on w l [3| n gl 4' lml g I! all Q K. FRACKE PRESSES Q 3Q 82 E g m g M: :5

Feb. 25, 1969 Filed Feb. 9, 1966 Feb. 25, 1969 K Filed Feb. 9, 1966 FRACKE PRESSES Sheet K. FRACKE Feb. 25, 1969 PRESSES Sheet 4 015 Filed Feb. 9, 1966 Feb. 25, 1969 K. FRACKE 3,429,174

PRESSES Sheet of 5 Filed Feb. 9. 1966 it tates US. Cl. 72453 Int. Cl. B213 9/18, 9/12; B30b 1/32 4 Claims ABSTRACT OF THE DISCLOSURE An impact forming machine having a pair of air operated press platens each provided with an expelling piston and cylinder device and a coupling piston and cylinder device. The expelling cylinder of each platen is connected with the coupling cylinder of the other platen through a blocking valve arranged, in one position, to couple the expelling cylinder with the coupling cylinder so that the platens can be brought together and, in another position, to isolate the expelling cylinder from the coupling cylinder and connect the expelling cylinder with the source of hydraulic pressure so that the platens can be moved apart.

The present invention relates to pressing machines operated by gas under pressure and having platens which are retracted by means of liquid under pressure. During movement of the platens together for striking a work piece, liquid under pressure flows from cylinders provided for the retraction of the platens through blocking valve means which are opened by means of a control device provided for causing the platens to operate.

One object of the present invention is to provide a pressing machine in which the kinetic energy of the platens can be high or can be low, that is to say the platens can be moved slowly towards each other.

A further object of the invention is the provision of a pressing machine whose impact energy can be varied.

A still further object of the invention is the construction of a machine in which the kinetic energy of the two platens is the same so that the frame and foundation of the machine are not subjected to excessive vibration.

A still further object of the invention is the provision of a machine with a higher efiiciency, that is to say one with smaller losses.

Further objects of the invention include the prevention of swinging or bouncing of the platens after impact in a simple manner, an increase in the number of impacts in a given time, an increase in the reliability of impact pressing machine.

A further object of the invention is the creation of an impact pressing machine which allows a sufficient cooling of parts which become hot during operation.

Further objects of the invention will appear on the following.

The invention consists in a machine for shaping work pieces by impact, comprising a pair of press platens, means for guiding the platens for movement towards each other, gas operated driving rams for moving the platens towards each other, each platen being coupled with a coupling piston arranged to receive liquid under pressure when the platens move together and an expelling piston adapted for expelling it when the platens move together and for use in moving the platens apart, and blocking valve means for coupling the expelling piston of one platen with the coupling piston of the other one and vice versa during movement of the platens towards each other.

atent F 3,429,174 Patented Feb. 25, 1969 'ice Preferably the blocking valve means comprise nonreturn valve means.

Preferably, also, the displacement of the expelling pistons, the capacity of ducts coupling them with the coupling pistons, and the displacement of the coupling pistons are such that when the blocking valve means are opened, the pressure in the connecting ducts falls to between 20 and 10% of the pressure in them when the platens are being moved apart by means of the expelling pistons.

In the case of the use of non-return valve means as blocking valve means, a relatively small hole can be provided to be opened shortly before the valve means is closed.

In accordance with a further preferred feature of the invention the blocking valve means and coupling pistons are so constructed as to oifer as little as possible resistance to the flow of liquid under pressure when the platens are moved together.

The length of stroke of the platens can be controlled by end switches so as to be steplessly variable.

The displacement of each coupling piston is preferably equal to the displacement of the expelling piston coupled with it.

Means can be provided for testing the setting of the blocking valve means for adjusting the speed of the platens independently of their energy.

Means can also be provided both for controlling the flow of hydraulic fluid to the expelling pistons and for cutting off this flow and for coupling them with the coupling pistons.

For inching the platens of the press by-pass valves can be provided by-passing the blocking valve means.

Preferably the cross section of duct means leading from the expelling piston and from the blocking valve means is so chosen that it corresponds to the receiving piston of the other platen so that the maximum speed of the pistons and the maximum speed of the pressure liquid are the same.

Some embodiments of the invention are now described with reference to the attached drawings.

FIG. 1 is a longitudinal section approximately in accordance with the line II on FIG. 2 of an impact shaping machine or press with a control device.

FIG. 2 is a section on the line IIII of FIG. 1.

FIG. 3 is a longitudinal section through a machine forming another embodiment of the invention.

FIG. 4 shows a blocking valve of the machine shown in FIG. 3 on a larger scale.

FIG. 5 is a front view of a third machine embodying the invention.

The press or machine shown in FIGS. 1 and 2 comprises a frame shown in FIG. 2 with stands 50 carrying rails 50a. Along these rails slide two platens 6 and 7 towards and away from each other. The first platen 6 is provided with a first die 8 and the second platen 7 is provided with a second die 9. The two dies fit together and correspond in shape to the shape of a work piece to be formed. If the platens operate in a vertical direction the work piece is placed in the second die 9 on the second platen 7.

Attached to the platens 6 and 7 near their centres there are ram plungers 6a and 7a connected with ram pistons 4 and 5 which in this particular embodiment of the invention serve simultaneously for driving the platens together and for moving the platens 6 and 7 away from each other before a working stroke is made. During a working stroke the pistons 4 and 5 expel hydraulic fluid from cylinders 11 and 12 and in view of this function the pistons are for the sake of convenience also termed expelling pistons though it is to be understood that the function of expelling hydraulic fluid during a working stroke and that of driving the platens 6 and 7 could be performed by separate pistons. The cylinders 11 and 12 surround the plungers 6a and 7a thus constituting the bases into which hydraulic fluid is forced during the movement of the platens 6 and 7 apart. On the other sides of the pistons 4 and there are the working spaces 1 and 2. These working spaces are connected respectively by openings 10: and 2a with an additional chamber 1b and 2b.

Rigidly connected with the cylinders 11 and 12 there are two coupling cylinders 13a and 13b containing coupling pistons or plungers 15a and 15b connected respectively with the corresponding platens 6 and 7. Connecting ducts 14a and 14b are connected with the cylinders 11 and 12 by means of entry openings 11a and 12a. The connecting ducts each lead to a coupling opening 13c in the coupling cylinders. These coupling openings 13c in the coupling cylinders can be closed by means of four blocking valve means 16a and 16b.

'Ducts a and 20b for gas under pressure are connected with an opening 19a in the additional chamber 2b of the second cylinder space 2 and with an opening 19b in the first cylinder space 1 and are joined with a pressure gas duct 20 whose end is connected with a gas container or bottle 21. The duct 20 running from the gas container 21 is connected with a reducing valve 22a, a hand valve 22b, a pressure gauge 22c, a nonreturn valve 22d, a safety valve 22s and a manually controlled release valve 22 The gas container 21 serves to supply the cylinder spaces 1 and 2 and the additional spaces 1b and 2b with gas under pressure which is stored in these spaces for driving the machine.

The machine is also provided with two pumps 23 and 24 drawing pressure liquid from a container 25 through tubular ducts 26 and 27. At positions adjacent to the pumps each of the ducts is connected with a safety valve 28a and a manual valve 28b provided with a pressure gauge 280. Further on each tubular duct is provided with a nonreturn valve 29. After this nonreturn valve the first tubular duct 26 branches into two ducts 30 which lead to connecting ducts 14a and 14b to the cylinder 11 of the first expelling piston 4 while the second tubular duct 27 branches into two ducts 31 which lead to the connecting ducts 14a and 14b connected with the cylinder 12 of the second piston 5.

These pairs of branched ducts 30 and 31 are connected with openings 17a and 17b up stream from the blocking valve means 16a and 16b in the connecting ducts 14a and 14b. The four blocking valve means are in the case of this particular embodiment of the invention in the form of nonreturn valves. As long as there is a greater pressure upstream from these nonreturn valves, that is to say in the branch ducts 30 and 31 than downstream from them, that is to say in the connecting ducts 14a and 14b, the nonreturn valves are opened and the pressure liquid from the two pumps 23 and 24 can flow into the connecting ducts 14a and 14b. If the pressure relationships are reversed, the nonreturn valves are closed. Each of the nonreturn valves has a moving part 16c which can block or allow to flow pressure liquid from the branch ducts 30 and 31 into the connecting ducts 14a and 14b and can also control the passage of pressure liquid from the coupling cylinders 13a and 13b through the coupling openings 130 into the connecting ducts. Thus if the passage from the branch ducts into the connecting ducts is completely-closed the passage from the couping cylinders to the connecting ducts is completely opened.

By means of adjusting slide valves 32a and 32b pressure liquid can be drawn off from the connecting ducts 14a and 14b and the coupling cylinders 13a and 13b through the openings 18a and 18b. These adjustment slide valves serve as by-pass valves bypassing the nonreturn valves and thus connecting the connecting ducts. If the adjustment valves 32a and 32b are opened the respective platens 6 and 7 move towards each other and pressure liquid flows out of the cylinders 11 and 12 into the coupling cylinders. If the adjustment valves are only partially opened for a short time, the platens can only move towards each other through a limited distance. These adjustment valves are therefore used for adjustment of the machine, that is to say for an inching of the platens towards one another.

Downstream from the nonreturn valves 29 the tubular ducts 26 and 27 are connected with ducts 26a and 26b whose ends are connected with a main control valve 33. The main control valve 33 has a moving part 33a which can block the connection of the ducts 26a and 27a with a duct leading back to the container 25. If the ducts are not blocked, the control valve is in the impact setting, that is to say the setting in which the platens 6 and 7 are driven together at high speed so as to subject the work piece to impact. In this position pressure liquid flowing from the pumps 23 and 24 along the tubular ducts 26 and 27 and the ducts 26a and 27a flows back via the main control valve 33 into the container 25. In this setting the pressure in the branch ducts 30 and 31 sinks and the blocking valve means 16a and 16b allow liquid to flow from the cylinders 11 and 12 to the coupling cylinders so that the platens 6 and 7 move together to produce impact.

The control devices of the machine also comprise auxiliary control valves 34 connected respectively with the first platen 6 and the second platen 7. The auxiliary control valves 34 are connected with ducts 35a and 35b leading from the openings 18a and 18b in the coupling cylinders 13a and 13b and are also connected with ducts 36a and 36b which are connected with the tubular ducts 26 and 27 upstream from the nonreturn valves 29. By the means of a moving part 34a the path from the coupling cylinders to the container 25 or from the tubular ducts to the container can be blocked or unblocked. A spring 37 in each of the auxiliary control valves presses the moving part 34a into a rest position in which passage of fluid under pressure is permitted from the tubular ducts 26 and 27 to the container 25 so that the pumps 23 and 24 idle. If the auxiliary control valves 34 are brought into such a position that their moving parts 34a are pressed against the pressure of the springs 37, pressure liquid can flow from the coupling cylinders but cannot flow from the tubular ducts so that liquid under pressure delivered by the pumps 23 and 24 flows through the nonreturn valves 29 and the branch ducts 30 and 31 to the pistons 4 and 5 serving to move the platens 6 and 7 apart. The machine is so made that each moving part 34a, which serves for the retraction of one of the pistons 4 and 5, 'sirnulatneously controls the return flow of liquid under pressure from the coupling cylinders 13a and 13b belonging to the respective pistons 4 and 5.

A further pump 38 pumps pressure liquid from the container 25 into the main control duct 39 through a nonreturn valve 40a. Behind the nonreturn valve 40a there is in the main control duct 39 an accumulator 40b, a safety valve 400, a pressure gauge 40d and a manual valve 402. The main control duct can be blocked at 41 by the moving part 33a of the main control valve 33 when the latter is brought into the impact position and the ducts 26a and 27a are connected with the container 25. The main control duct 39 branches into two ducts 42a and 4212 which are connected with the auxiliary control valves 34 and control their moving parts 34a. These ducts 42a and 4212 can be blocked by magnetically controlled valves 43 and 44 with outlet ducts 45a and 45b for returning pressure liquid to the container 25. Upstream from the main control valve 33 there is a branch duct 46 which is connected with the control valve 33 by a magnetically controlled valve 47 in such a manner that when the control valve 47 is operated liquid under pressure passing through it causes the main control valve 33 to be set in the impact position. The magnetically controlled valve 47 is also connected with a further magnetically controlled valve 48 serving for moving the control valve 33 out of the impact position.

When the platens of the machine are moved apart only the first magnetically controlled valve 48 is opened so that the moving part 3341 of the main control valve 33 blocks the passage from the tubular ducts 26 and 27 to the container with the help of a spring 49 pressing it down. By means of a manual switch (not shown) the magnetically controlled valves 43, 44, 47 and 48 are switched round so that the magnetic valve 48 is closed while the valves 47 and 43 and 44 are open. However the magnetically controlled valves 47 and 48 associated with the main control valve are only open for a short time while the control valves 43 and 44 associated with the auxiliary control valves remain open for a longer time. Owing to the short length of time for which the valves 47 and 48 are operated, the moving part 33a of the main control valve is brought into the impact position and the platens of the machine are driven together so as to exert an impact on the work piece. In this case the main control duct 39 is blocked at 41 so that the auxiliary control valves 34 hardly act despite the fact that the valves 43 and 44 are open. At the end of the impact the main control duct is opened at 41 so that the auxiliary control valves 34 block the passage of pressure liquid from the tubular ducts 26 and 27 to the container 25 and the platens of the machine are again moved apart.

The platens continue to move apart until the auxiliary control valves 34 are operated by means of the magnetically controlled valves 43 and 44. This can be carried out by means of the manually controlled valve already mentioned above but can also be carried out automatically by means of the platens 6 and 7. For this purpose, as shown in FIG. 5, each platen 6 and 7 can be provided with a rack 57. The racks 57 are connected at their ends adjacent to the platens with end switches 58a and 58b which are operated by cams 59 on the platens. The end switches 58a and 58b are connected in a conventional manner well known to those in the art with the magnetically controlled valves 43 and 44 associated with the auxiliary control valves 34 shown in FIG. 1. The racks 57 can be adjusted by means of a pinion 60a so that the end switches 58a and 58b are moved in relation to each other. The machine has a pair of racks on each side of it each provided with end switches. This enables a series of impacts to be performed under the control of the first pair and further impacts to be performed under the control of the second pair which has been put at a different setting. Also more than two pairs of racks can be provided. The machine is so constructed that the stroke of the platens and therefore the energy setting can be adjusted steplessly by means of the opposite end switches 58a and 58b. This construction of the machine makes it necessary to retract the two platens independently of each other.

The degree of movement of the moving parts 160 of the nonreturn valves 16a and 16b and therefore the cross section of the passage through them available for pressure liquid flow can be altered by means of setting screws 60. The machine is so constructed that by adjusting the strokes of the moving parts 160 of the blocking valve means 16a and 16b the speed of the pistons 4 and 5 can be adjusted independently of the energy of the platens since the energy of the platens depends upon the gas pressure in the cylinder spaces 1 and 2.

During movement of the platens 6 and 7 towards each other the liquid under pressure flows from the cylinders 11 and 12 through the blocking valve means or nonreturn valves 16a and 16b into the coupling cylinders 13a and 13b. To prevent any braking eflect on the pressure liquid at any point and any acceleration of it, it is convenient if the area of the cross section of each of the connecting ducts 14a and 14b and of the respective blocking valve means is so chosen as to be equal to the annular working face of the piston 4 or 5 to which the connecting duct leads so that the maximum piston speed and the maximum speed of the liquid are the same. Preferably the machine is adapted for relative speeds of the platens of up to 22 metres per second. In order to permit a flow of the whole of the pressure liquid compressed in one cylinder space during impact into the coupling cylinders so that it does not have to partially be allowed to escape it is expedient to make the displacement of the coupling piston of one platen equal to the displacement of the piston 4 or 5 of the other platen. It is in this respect irrelevant whether the two platens have the same mass, the same speed and the same degree of travel for impact or whether, for example, the first platen has a larger mass and a lower speed and a lower travel than the first platen which would then have a smaller mass and a higher speed. At this point it is appropriate to mention that the ratio of the product of half the mass moved by one platen and the square of the velocity of the platen can be any desired value for the two platens as long as the product of the mass and speed for the two platens is the same. It is also an advantage if the pressure of the pressure liquid for retracting the platens, the capacity of the cylinders 11 and 12, of the connecting ducts and of the coupling cylinders are so chosen that on opening the blocking valve means the pressure in the cylinders 11 and 12 falls to between 10 and 20% of the pressure during retraction of the platens.

In the pressing machine shown in FIG. 3 supported on a lower frame part 50b, the individual parts are denoted by the same reference numerals as the parts in the machine shown in FIGS. 1 and 2. The machine can be provided with a control device as shown in FIG. 1. In this machine it can be seen that the cylinder spaces 1 and 2 and the cylinders 11 and 12 are connected by walls 3 between which the platens 6 and 7 and the connecting ducts 14a and 14b are situated. It can also be seen from the drawing that the pistons 4 and 5 and their plungers 7a and 7b are provided with stationary seals 10.

This machine dilfers from the machine shown in FIG. 1 in that the coupling cylinders 13a and 13b are fixed firmly to the platens 6 and 7 while the coupling pistons or plungers 15a and 15b are firmly fixed to the frame, that is to say the cylinders 11 and 12.

The platens 6 and 7 are provided with guide holes 51 surrounding the connecting ducts 14a and 14b so that there is no special necessity for the provision of guide rails for the platens. Also the coupling cylinders 13a and 13b, fixed to the platens surround the connecting ducts.

One of the blocking valve means 16a or 16b in the form of a non-return valve, of the machine shown in FIG. 3, is shown in FIG. 4.

The blocking valve has an immovable valve casing 16d which forms a part of the stationary coupling piston 15b. It is also provided with a moving part 160. On one side the moving part is connected by a branch duct 30 and an opening 17a with pressure fluid delivered by a pump. Pressure fluid coming along this path causes the blocking valve means to block the connecting duct 14a. Liquid under pressure coming from the pump passes through a relatively small hole 55 in the moving part 160 into the connecting duct 14a and thence passes into the respective cylinder space. For bringing about an impact stroke of the machine, the pressure of the pressure liquid in the opening 17a is decreased considerably as described above so that the moving part 160 moves back to an abutment 52 in the valve casing 16d. The pressure liquid flows from the connecting duct 14a into an annular valve space 53 running around the moving part 160. Since the platen 7 moves upwards the valve space 53 is increased in size. The increased valve space 53 constitutes the cylinder space of the coupling cylinder 13a. Since the liquid under pressure flowing from the connecting duct 14a into the coupling cylinder 13a reverses its direction of flow in the valve space 53, the blocking valve means, in this case the moving part 160 and the stationary coupling piston b, that is to say the valve space 53 formed by it, is formed, as can be seen from FIG. 4, so as to oifer as little resistance as possible to the flow of the pressure fluid. This important feature substantially reduces losses of power in the machine. When the nonreturn valve is closed again and the platen 7 shown in FIG. 4- moves down again, liquid under pressure is pressed out of the coupling cylinder 13a, that is to say the valve space 53 through a hole 54 and through the duct 35b, as described above, back into the container 25.

The hole 55, which at one end is connected with the connecting dut 14a increases the reliability of the machine in operation. Its other end is connected, when the nonreturn valve is closed or is only slightly open, with a recess 56 in the valve casing 161! which is connected with the opening 17a. (The liquid in the connecting duct 14a, which may be under a high pressure, can flow out through the recess 56 and, since it cannot escape from the recess, can close the blocking valve means again. When the blocking valve means is wide open, that is to say up till impact occurs, the other end of the hole 56 is closed. The ma chine is then so set that the controlled non-return valve has only the small hole 55 which is only opened shortly before the closing of the valve and thus prevents a fall in pressure upstream from the nonreturn valve in the case of: a leakage of the control valves 34 of the hydraulic control arrangement so that undesired opening of the nonreturn valve leading to an unintentional operation of the pressing machine is avoided.

I claim:

11. A machine for shaping work pieces by impact, comprising a pair of press platens, means for guiding the platens for movement towards each other, gas operated driving rams for moving the platens towards each other, expelling cylinders, expelling pistons movable within said expelling cylinders and attached respectively to the two platens, coupling piston and cylinder devices connected with the platens, the coupling cylinders being arranged to receive pressure liquid from the expelling cylinders when the platens move together, means for hydraulically operating the expelling pistons so as to move the platens apart, and nonreturn valve means for coupling the expelling cylinder of each platen with the coupling cylinder of the other platen during the movement of the platens towards each other, wherein a pressure fluid duct is provided and the nonreturn valve means is provided with a movable part which is connected on one side with the pressure liquid of the expelling cylinders and on the other side with said duct, and means defining a relatively small hole which is located so as to be opened shortly before the valve is closed in order to connect the expelling cylinder with said duct whereby unintentional operation of the machine is prevented in the case where a fault de velops which reduces the pressure in the said duct.

2. A machine for shaping work pieces by impact, comprising a pair of press platens, means for guiding the platens for movement towards each other, gas operated driving rams for moving the platens towards each other, expelling cylinders, expelling pistons movable within said expelling cylinders and attached respectively to the two platens, coupling piston and cylinder devices connected with the platens, the coupling cylinders being arranged to receive pressure liquid from the expelling cylinders when the platens move together, means for hydraulically operating the expelling pistons so as to move the platens apart, and blocking valve means for coupling the expelling cylinder of each platen with the coupling cylinder of the other platen during the movement of the platens towards each other, wherein the blocking valve means is provided with moving parts having an adjustable degree of movement whereby the impact speed of the platens can be adjusted.

3. A machine for shaping work pieces by impact, comprising a pair of press platens, means for guiding the platens for movement towards each other, gas operated driving rams for moving the platens towards each other, expelling cylinders, expelling pistons movable within said expelling cylinders and attached respectively to the two platens, coupling piston and cylinder devices connected with the platens, the coupling cylinders being arranged to receive pressure liquid from the expelling cylinders when the platens move together, means for hydraulically operating the expelling pistons by a flow of liquid under pressure to the expelling cylinders so as to move the platens apart, and blocking valve means for coupling the expelling cylinder of each platen with the coupling cylinder of the other platen during the movement of the platens towards each other, wherein the blocking valve means is also arranged to control that flow of liquid under pressure to the expelling cylinders and to prevent such flow.

4. A machine for shaping work pieces by impact, comprising a pair of press platens, means for guiding the platens for movement towards each other, gas operated driving rams for moving the platens towards each, expelling cylinders, expelling pistons movable within said expelling cylinders and attached respectively to the two platens, coupling piston and cylinder devices connected with the platens, the coupling cylinders being arranged to receive pressure liquid from the expelling cylinders when the platens move together, means for hydraulically operating the expelling pistons so as to move the platens apart, and blocking valve means for coupling the expelling cylinder of each platen with the coupling cylinder of the other platen during the movement of the platens towards each other, wherein an adjustment valve couples the expelling cylinder of one platen with the coupling cylinder of the other for an inching together of the platens, the blocking valve means is provided with a moving part, a duct connects pressure fluid with one side of the movable part and a main control valve connected with the duct is provided for decreasing the pressure or the pressure fluid so that the movable part is moved into a position in which the expelling cylinders are connected with the coupling cylinder during operation of the machine.

References Cited UNITED STATES PATENTS 2,583,049 1/1952 Hartemann 72--22 2,655,002 10/1953 Terhune 72407 3,209,578 10/ 1965 Muller 72407 3,329,003 7/ 1967 Bakhtar 72453 CHARLES W. LANHAM, Primary Examiner.

G. P. CROSBY, Assistant Examiner.

U .8. Cl. X.R. 72407; -269 

